Entry(spawn) points for anything on map.

[Valor]

Generally animals, visitors and enemies spawn on any discovered map edge. But I have an issue, via mod I had a map generated that was a river cutting through mountain. Montain is mostly solid with few crevices here and there serving as valleys, where plan life and animals are. River is encompased by a lot of shalloow wats so movement is possible on both side with few wade points between the sides possible. After the generation I noticed the one end of the river is inaccessible (due to few missing spots of shallow water). I fixed it with dev mode. Every pawn can now use it (and some often does) to leave the map, but nothing ever spawns on that end. Only the other end is used to spawn everything (both sides of that end) So my questions:

Are the spawn points determined on map creation?
Can I change (add) spawn point manually? Via dev mode or save file editing?

Thank you.